site/contents/reference-logic.md
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----- content-type: "page" title: "logic Module" ----- {@ _defs_.md || 0 @} {#op||>||{{a1}} {{a2}}||{{b}}|| > Returns {{t}} if {{a1}} is greater than {{a2}}, {{f}} otherwise. > > %note% > > Note > > > > Only comparisons among two numbers or two strings are supported.#} {#op||>=||{{a1}} {{a2}}||{{b}}|| > Returns {{t}} if {{a1}} is greater than or equal to {{a2}}, {{f}} otherwise. > > %note% > > Note > > > > Only comparisons among two numbers or two strings are supported.#} {#op||<||{{a1}} {{a2}}||{{b}}|| > Returns {{t}} if {{a1}} is smaller than {{a2}}, {{f}} otherwise. > > %note% > > Note > > > > Only comparisons among two numbers or two strings are supported.#} {#op||<=||{{a1}} {{a2}}||{{b}}|| > Returns {{t}} if {{a1}} is smaller than or equal to {{a2}}, {{f}} otherwise. > > %note% > > Note > > > > Only comparisons among two numbers or two strings are supported.#} {#op||==||{{a1}} {{a2}}||{{b}}|| Returns {{t}} if {{a1}} is equal to {{a2}}, {{f}} otherwise. #} {#op||!=||{{a1}} {{a2}}||{{b}}|| Returns {{t}} if {{a1}} is not equal to {{a2}}, {{f}} otherwise. #} {#op||and||{{b1}} {{b2}}||{{b3}}|| Returns {{t}} if {{b1}} is equal to {{b2}}, {{f}} otherwise.#} {#op||boolean?||{{any}}||{{b}}|| Returns {{t}} if {{any}} is a boolean, {{f}} otherwise. #} {#op||dequote-and||{{a1}} {{a2}}||{{b}}|| > Short-circuited logical and. It performs the following operations: > > 1. Pops {{a1}} and {{a2}} off the stack. > 2. Dequotes {{a1}}, if {{f}} is on the stack, it pushes {{f}} on the stack and stops, otherwise it carries on. > 3. Dequotes {{a2}}. > 4. If {{a2}} is {{t}}, it pushes {{t}} on the stack. > > > %note% > > Note > > > > {{a1}} (and {{a2}}, if dequoted) must evaluate to a boolean value, otherwise an exception is raised. > > > %sidebar% > > Example > > > > The following program returns {{f}} and never executes the second quotation. > > > > "test" :x (x number?) (x 5 <) dequote-and #} {#op||dequote-or||{{a1}} {{a2}}||{{b}}|| > Short-circuited logical or. It performs the following operations: > > 1. Pops {{a1}} and {{a2}} off the stack. > 2. Dequotes {{a1}}, if {{t}} is on the stack, it pushes {{t}} on the stack and stops, otherwise it carries on. > 3. Dequotes {{a2}}. > 4. If {{a2}} is {{f}}, it pushes {{f}} on the stack. > > > %note% > > Note > > > > {{a1}} (and {{a2}}, if dequoted) must evaluate to a boolean value, otherwise an exception is raised. > > > %sidebar% > > Example > > > > The following program returns {{t}} and never executes the second quotation. > > > > "test" :x (x string?) (x quotation?) dequote-or #} {#op||dictionary?||{{any}}||{{b}}|| Returns {{t}} if {{any}} is a dictionary, {{f}} otherwise. #} {#op||float?||{{any}}||{{b}}|| Returns {{t}} if {{any}} is a float, {{f}} otherwise. #} {#op||or||{{b1}} {{b2}}||{{b3}}|| Returns {{t}} if {{b1}} or {{b2}} is {{t}}, {{f}} otherwise.#} {#op||integer?||{{any}}||{{b}}|| Returns {{t}} if {{any}} is an integer, {{f}} otherwise. #} {#op||not||{{b1}}||{{b2}}|| Negates {{b1}}.#} {#op||number?||{{any}}||{{b}}|| Returns {{t}} if {{any}} is a number, {{f}} otherwise. #} {#op||quotation?||{{any}}||{{b}}|| Returns {{t}} if {{any}} is a quotation, {{f}} otherwise. #} {#op||type?||{{any}} {{sl}}||{{b}}|| Returns {{t}} if the data type of {{any}} is the specified type {{sl}}, {{f}} otherwise. #} {#op||xor||{{b1}} {{b2}}||{{b3}}|| Returns {{t}} if {{b1}} and {{b2}} are different, {{f}} otherwise.#} |